Anti-icing and engine cooling system for airplanes



L. DEWAN ANTI-ICING AND ENGINE COOLING SYSTEM FOR AIRPLANES Filed March 20, 1943 INVENTOR Leon Dewa/w ORNEY maybe driven by an'electric motor.

Patented Dec. 26, 1944 ANTl-ICINGAND ENGINE COOLING SYSTEM ron AIBPLANES V Leon Dewan, hrvernANQY. n Application March 20,1943, sea 479,838 reclaims. (oi 244 13 4) My invention relates; to a combined system for [preventingicing and for cooling the-engines of.

. "same time thecombustion heateris automatical I 'ly broughtinto playby thelowered' temperature airplanes such as disclosed inmy copending application Serial Number 466,122, filedNovember 19,1942. M i n One object of my invention is to keep the circulating coolant of such a system within a constant temperature. range regardless oi atmospheric temperature change and at the same. time i c to provide ample heat forpreventing icing when itisneeded. l Another object is to provide a unified system: wherein the heat for the cabin is derived from the same source as the heat for preventing icing. Another object is to provide means whereby in case of engine failure the anti-icing system will be maintained and the engine kept warm to make re-starting easy or possible. i 1

Otherobjects and advantages of my improved system will be apparent from the description thereof to follow. it

- ance withcabin temperature; 1 n n i Fig; 1 is a schematic illustration of my imof theliquid so that the heated circulating fluid n serves to' maintain anti-icing conditions andto" keep the-motor warm to-facilitate restarting; j

The electric motormay serve asap generator under ordinary conditions for adding to the storage battery charge and the same emergencysystem may be used on the ground to warm up the engine and coolant before startingunder lowtem- 'perature conditions. y y

A part of the liquid issuing from theheater outlet is led to an air-liquid heat exchange which is used to heat air for thecabin and cockpit, the flow in this branch being controlled in'acjcord f proved system and its operation.

According to the invention, special thin radiators line the leading edges of the wings and other anti-icingpartsofthe plane, one side of the radiators formingtheoutersurface of theplane and being offia porous metal such as sintered aluminum so that some. of the. anti-freeze. liquid Fig. 2 is a view in side elevation offone form j the improved special heater may take.

Referrlngto the drawingfin Fig. 1, a 3 circulates an anti-freeze liquid such as ethylene "glycol for example through the cooling jacket] coolant may be exuded therefrom when necessary. The combined heat and propertiesof the anti-freeze at the wing surface formthe anti- -as represented at 4 of an airplane engine 5, and through a heater ewnos function is to maintain or raise the temperature of the liquid when necessary. The liquid passes througha centrifuge I which extracts any gases therefrom and on to a header tank 8 from which it is dis-' icing means, and this liquid minus the heatthus dissipated and lost becomes and efficient-coolant.

upon return to the. engine.\,

Ordinarily the radiators are Joy-passed thermostatioallyaccording to the coolant tempera;

ture, the radiators receiving less flow with low-a In this invention, however,

ering temperature. when icing conditions 1 occur, the by-pass is bridged so that the radiators receive a fuller flow of liquid which iscontrolled by an icing indicator according to the severity of theicing conditions, or by a thermo element to increase the flow through the radiators with. lowered temperature of the liquid.

The coolant passes through a special heater between the engine and the radiators, this heater operating only when the liquid falls below a predetermined temperature. This operating point is raised when icing conditions occur. The heater may be of the combustion or exhaust gas exchange type or a combination of the two.

tributed to the various points. One branch 9 passes through the air-liquid exchanger I I! which is provided with a fan I l for circulating heated air for the cabin. The thermostat I2 in this branch regulates the flow according to cabintem- The coolant pump is turned by the engine through a magnetic clutch which can be released when the engine fails so that the pump At the perature tokeep it constant; y

Branch l3 leads to the anti-icing radiators. and is by-passed by thepipe l4 leading to the return line. Thefby-pass thermostat valve 15 controls the: relative flow so as to decrease the same through theradiator's in proportion to lowered temperature of. the liquid. This valve is bridged by the-pipe 16 whose entrance is controlled by' asolenoid operated valve 11.

Branch 3 leads to an auxiliary radiator l9 whose surface may be of solid aluminum and which may form a part of the surface of the plane which does not particularly requireantiicing measures. The thermostat 20 controlling the by-pass 2! for thi radiator also reduces the flow through the radiator in proportion to lowered liquid temperature but closes'completely at a comparatively high temperature, this radiator. being in use only in a hot climate or where the anti-icing radiator is completely disabled. v

The returning liquid mingies'in the tank 22' and passes through main pipe 2; at the topmost part in which is. located the reservoir and ex- 'a,see,oso I ter 30 to open the. flow to the radiators through a pipe I Ii bridging the by-pass thermo-valve II.

pansion tank 24 whichreplenishes any liquid lost through exudationv and other causes and allows for thermal expansion of the liquid. This is supplied from a branch" from the centrifuge I. inthe usual manner.

The thermometer 28 indicates the temperature of the liquid as it comes from the,anti-icing radiatorandmay be used to control the 'valve I 1 36 in some cases under icing conditionsto regulate the temperature in theradiator line. This is indicated by the short dotted lines issuing from members 28 and 26. 5

The thermo-control 21 in the main line controls the heater 8 by turning the control 28' on and off perature limit on the thermostat "21 may be. raised as described by actuation through control line 35 and the heater operated at a higher level. 1 The flow through pipe l6 may be regulated in accordance with the temperature of the radiator within predetermined temperature limits by electric apparatus through control lines 22 indicated by dotted lines. The control apparatus for this purpose is well known and needs no detailed description, 'I'he;temperaturelimits at which the heater is operated may be changed by suitable Y switchingto' a diflerent set oi contacts on the theme control 21' and this may be controlled by a central switching apparatus Ill tor-setting antiicing measures into motion. The same apparatus is used to operate valve l1 and open the. flow control lines.

Theco'olant pump 2 is turnedby engine coupling through electro-magnetic clutch II' which example, it may assist in char ing the storage batteries during flight.

The switch apparatus 34 controls the release of tor int a motor inconnection with the nature 01' its use. g

The operation of the system is as follows: under normal flying eonditionswhere the outside temperature is high, the anti-icing radiators would- 4 7 through the radiators as indicated by the dotted .magneticclutch II and also effects whatever circuit changes are necessary to convert the generareceive the full'flow of liquid through valve [5 and the auxiliary radiator would receive a flow depending on the outside temperature plus engineconditions. Heater ,6 would be inoperative.

-As the outside temperature lowers, the valve 20 of the auxiliary radiator is closes completely at a comparatively high point and the valve. I 5' of the anti-icing radiators would reduce the flow through same in accordance with the falling temperature, though never completely closing as some little flowmust remain to keep the liquid in the radiators from congealing when the temperature isex'tremely low. The liquid then would be almost completely by-passed through pipes l4 and 2| and would maintain its temperature for the cabin heating through pipe 9" and for the normal engine operation. If however the outside temperature still descends, the lowering of the liquid temperature below a predetermined point, say 190 R, will cause the thermo control 21 to operate the heater to maintain normaiternperature, the

heater either being varied gradually to balance the temperature ormerely discontinued'when the temperature arises above another predetermined point, say 250 F.

When icing conditions, occur, the solenoid valve I1 is actuated through theanti-icing control'cen- The temperature of the liquid in the main line would tend to descenddue to this flow except that the thermostat 2 automatically operates the heater at a predetermined point to maintain the temperature normal so that the radiators now 7 receive a full new of liquid at a comparatively high temperature. To increase the anti-icing effect under severe. icing conditions, the temretum liquid as measured by thermo device 26, by

suitable control therefrom to the valve .38, as

shown by the partially extended dotted lines, or it' maybe varied in accordancejwith severity of icing conditions in conjunction with an icing indicator. The .degrees of temperature mentioned are given only for the purpose of illustration'andmay vary in accordance with the type of operation. g r

As previously described, the coolant pump- 8 turns the generator 33 ordinarily to help charge the storage batteries, while at any time the v 7 switching apparatus 34 may be actuated and the magnetic clutch 3| released to cause generator 33 to act as, a motor and keep the pump and coolant in operation. This is most necessary in case of engine failure; The heater is automaticallybrought into operation-at the same time by the lowered liquid temperature. It is necessary how-. ever to prevent operation of the heater in case 7 both the engine and the electric motor fail' i'or any reason in which casefia centrifugally operated switch turned by the pump shaft may keep the heater control circuit intact only while the pump shaft is turning. This combination of'electricaliy driven pump and combustion heater may be operated before the engine is started'on the; ground in cold weatherto warm the engine and. coolant quickly and satisfactorily, particularly for emergency starts in cold climates. 7 The system for creating occasional pressure in the radiators to cause exudation of anti-freeze and the leak test with automatic shut-oi! of leaking radiator units, whileiundamentally similar to that described in my copending application, Serial Number .466,122, differs in design. The

leak test is asiollows: the gang operated valves 31 and 38 normally allow full flow of thecoolant. However at suitable intervals both sets of valves are operated momentarily and caused to constrict; the now by means of solenoid apparatus 3! A through central switch 40 to such an extent as tocause the pressure indicating and control system as represented by the pressure meter and the pressure meters 42 to be sensitive to any tall or pressure inv a unit radiator due to a leak. The

test may be carried out periodically through auto- 1 matic means operating control 45' at regular intervals. Well known remote indication system may transmit to the cockpit the movements of meters 4| and 42 located near the engine and cooling system. Ii the pressure in one unit radiator as shown by its meters 42 compared to meter 4| is below that of the rest, a warning maybev operated and its valves 43 are automatically: shut as described in detail in my copending application, Serial Number 466,122.

When icing conditions occur and it is desired to cause an exudation of anti-freeze liquid, the pressure in the radiators must be momentarily raised to produce this result. This is accomplished by actuating the solenoid valve 44 to close the radiator pipe behind meter ll. The valves "38 are also closed. The small pump is then operated briefly, this pump being Just for the pur-' pose of applying the required pressure independently of the rest of the system. This operation is performed by central switching apparatus 45 operating through control lines 46, 41 and 48.,

The actualamount of anti-freeze liquidltobe exuded is comparatively slight since heatis already assisting in anti-icing the wing surface.

The porosity of the sintered metal surface may be of a fine order so that the surface is smooth .and the amount of liquid exuded under ordinary need not be large because the engine itself supplies the main heating requirements.

In aircraft designed for long dlstancefiights and where fuel consumption must be limited, the

. V 3- tained within a normal operating. range under excessive cooling conditions.

3. In an aircraft, the combination of an engine, a wing radiator mea'ns for circulating a .liquid coolant, said liquidbeing heatedby they engine cooling jacket. means forheating said a liquid supplemental tosaid cooling jacket and], i means for increasing the flow of liquid through;

the radiator under icing conditions and means for increasing the amount of supplemental heat added to the liquid accordingly wherebythe v coolant temperature ismaintained under .the

increased flow.

4. In an aircraft, the combination, of an en gine, a wing radiator, means for circulating a liquid coolant, said liquid being heated by the. engine cooling jacket, and an exhaust gas heat' exchanger for heating the liquid supplemental to the engine cooling Jacket, and means for varying the amount of supplemental heat added to the liquid independently of the heat imparted by the cooling jacket.

system illustrated in Fig. 2 may be used for the heater. Here a part of the hot exhaust gas in pipe' 49 is diverted into the core 50 of the exchanger portion through which the liquid passes by means of the pipes 5|. This is used ordinarily under icing conditions in the same manner as has been previously described in connection with the heater 6, the hot gas being admitted as the ,port or valve 52 is opened. However incase of engine failure or 'where it is desired to warm a still engine, a supplementary combustion heater I3 is operated and the hot gastherefrom is admitted into the chamber 54 to heat the core in lieu of the exhaust gas. The valve 55 which admits the combustion gases is closed when the exhaust gas valve is open and vice versa. The valve 12 which controls the flow of liquid to the cabin heat exchanger in may then be partly or fully closed to conserve fuel or heat for this process when necessary. v

In large transport planes where cabin heating requirements are high, the heat exchanger may be of a type which uses the full flow of the ex-' haust gas.

I claim:

1. In an aircraft, the combination of an engine, a wing radiator, means for circulating a liquid coolant, said liquid being partly heated by the engine cooling jacket and means for heating said liquid supplemental to said engine cooling Jacket and means for varying the amount of supplemental heat added to said liquid independently of the heat imparted to said liquid by the cooling jacket.

2. In an aircraft, the combination of an engine, a wing radiator, means for circulating a 'liquid coolant said liquid being heated by the engine cooling jacket and means for heating said liquid supplemental to-said cooling jacket and.

means :for varying the amount of supplemental heat added to the liquid independently of the heat imparted to the liquid by the cooling jacket whereby the temperature of the liquid is main- 5. In an aircraft, .the'combination of an engine, a wing radiator, means for circulating a liquidcoolant, said liquid being heated by the engine cooling Jacket, an independent fuel com bustion heater for heating the liquid supplemental to the cooling Jacket, and means for varying the supplemental heat imparted to the liquid thereby for maintaining the coolant temperature under varying atmospheric eflect on the'wing radiator.

.6. In an aircraft, the combination of an engine, a'wing radiator, means for'circulating a liquid coolant, said liquid being partly heated by the engine cooling jacket, means comprising a. heat exchanger for heating the liquid supplemental to the engine surface an independent fuel combustion heater and means forleading exhaust gas through the heat exchanger andmeans to lead combustion heater gas through said. exchanger whereby either gas may heat the same. '7. In an aircraft, the combination of an engine, a radiator therefor for heating the ice accumulating portion of the aircraft, means for circulating a liquid coolant, a pipe line by-passing the radiator with automatic means to decrease the flow through the radiator when the temperature .of the liquid falls and means operable at will under icing conditions for reversing the effect of the latter means whereby the flow of the liquid increases with falling temperature of the same. n

8. In an aircraft, the combination of an engine, a wing radiator, means for circulating a liquid coolant through the wing radiator and through the cooling Jacket of the engine, means for automatically controlling the flow of the liquid through the radiator according to ambient temperature and independent means for varying at will the flow'through the radiator to increase said flow under icing conditions.

9. In an aircraft-the combination of an engine, a wing radiator, means for circulating a liquid coolant through the radiator and through the cooling jacket of the engine whereby the temperature of the radiator is maintained above the ambient for engine heat dissipation and independent means for raising. the temperature of the liquid passing through the radiator-under icing conditions above the point which would otherwise normally prevail for preventing ice formation.

10. In an aircraft, an engine warming system having in combination an engine, a radiator, a

coolant pump therefor, means for heating the coolant supplemental to the cooling jacket of said engine, means for driving the coolant pump 12. In an aircraft, the combination of an engine, a wing radiator, means for circulating a liquid coolant through the engine cooling jacket and the wing radiator whereby the temperature of the wing radiator is raised above the ambient atmospheric temperature to dissipate engine heat, means for regulating the liquid flow through the wing radiator to'vary its temperature in accordance with variation in atmospheric temperature and independent means operable at need under icing conditions for increasing the flow of liquid through the radiator above that ordinarily provided by the regulating means whereby the temperature of the radiator is raised air-liquid exchanger in said pipe line, means for 15 for preventing ice formation. passing theliquid therethrough and means 00- acting with said exchanger for heating the cabin of the aircraft.

e v V V 7 LEON DEWAN, 

